[pkg] Improve mocked module detection by combining mocked object errors with the rest of the errors in PackageExporter (#74315)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/74315
Now instead of spitting out a NotImplemented Error when the Package Exporter finds an object for a mocked module, it combines these errors with the rest of the Packaging Errors of PackageExporter to get something like
```
torch.package.package_exporter.PackagingError:
* Module was mocked out, but is still being used in the package.Please intern or extern the mocked modules if objects are supposed to be inthe package.
package_a
Context: Object(s) '['PackageASubpackageObject']' from module package_a was mocked out during packaging but is being used in resource - obj.pkl in package obj.
package_a.subpackage
Context: Object(s) '['PackageASubpackageObject']' from module package_a.subpackage was mocked out during packaging but is being used in resource - obj.pkl in package obj.
```
This makes it significantly easier to fix mocked object errors as they all should appear at once.
Test Plan: Imported from OSS
Reviewed By: d4l3k
Differential Revision: D34951973
Pulled By: PaliC
fbshipit-source-id: 01ee4ba3767967ef9a9bcd69ad86362ebc100b2d
(cherry picked from commit 900edd270ee8f5802fc6e56df08fff6b073ac6f2)
